Apparatus and method for replacement of a bearer member of a longitudinal bearer joint in a motor vehicle body

ABSTRACT

A bearer joint for a vehicle bodywork, and in particular a longitudinal front bearer joint, and a method for placing a aluminum bearer member on the bearer joint in the vehicle bodywork. The bearer joint comprises a cast aluminum connector for joining together a first forward bearer member and a second rearward bearer member. The connector includes a tubular aluminum recess or socket for receiving the rearward end of the first aluminum bearer member which is fixed thereto by a transverse weld seam at the front receiving edge of the socket. A plurality of offset thickened regions with through holes are provided to the periphery of the socket. To replace a damaged front bearer member, the weld is cut and the damaged front bearer is withdrawn from the socket. A repair kit is provided which includes a replacement front bearer member and a platelike insert sized to fit within an end of the replacement bearer member. The bearer member and insert are provided with offset holes which correspond in number and location to the holes provided to the socket. Threaded screw and/or bolt fasteners are used to secure the insert and replacement bearer member within the socket.

FIELD

The present invention relates generally to fabrication and repairtechniques for a motor vehicle bodywork. More particularly, theinvention relates to an apparatus and method for replacement of analuminum bearer member in a longitudinal bearer joint in a vehiclebodywork.

BACKGROUND

From published European Patent document EP-PS 146 716, it is known howto produce the load-bearing structure of a vehicle bodywork by usingnodal connector elements for joining together hollow section bearers.Extruded aluminum sections are used as the hollow section bearers andcast aluminum joint pieces are used as the nodal connector elements.Such a bodywork design offers improved corrosion resistance and weightsavings.

It is also known from the prior art how to construct a hollow-sectionlongitudinal bearer assembly of a vehicle frame from a plurality oflongitudinal bearer members. These individual longitudinal bearermembers are joined together, in end to end fashion, by a surroundingweld seam beginning with the forward most bearer member and workingrearwards. Each successive longitudinal bearer member beginning with theforwardmost bearer member is dimensioned with a progressingly greaterwall thickness and/or is made of a progressively higher grade ofmaterial than its preceding bearer member such that the resultinglongitudinal bearer assembly has a graduated stiffness or resistance todeformation which increases toward the middle of the vehicle. Thus, inthe event of a minor accident, usually only one or two of theforwardmost bearer members will experience deformation without damage tothe adjacent rearwardly disposed bearer members. This arrangementgreatly simplifies the repair of the vehicle front and also avoids anundesirable total deformation of the vehicle frame in less severeaccidents.

In the vehicle frame of the type described, the repair of a deformedlongitudinal bearer assembly is accomplished by cutting out the damagedbearer members and welding on new bearer members. For the case where thelongitudinal bearer assembly comprises sheet metal stampings, thedescribed repair procedure does not give rise to any major structuralproblems since the original strength of sheet metal is substantiallyretained even after welding.

European Patent document 0146 716 discloses a positive-lockingconnection scheme in a longitudinal bearer assembly in a vehicle bodywherein an aluminum bearer, formed as an extruded section, is insertedinto a tubular aluminum recess or socket formed as a cast piece. Thealuminum bearer is then welded to the front edge of this tubular recessby a surrounding weld seam. Such a connection is stable and economical.

However, it is well known that the thermal welding of heat treatablealuminum alloys produces a significant decrease in the strength in thematerial in the so-called "zone of thermal influence" immediatelyadjacent the weld seam. A surrounding weld connection, such as is usedin the above-described bearer joint, is especially critical, since itproduces a weakening in a continuous transverse plane. The decrease inthe strength of the bearer joint caused by the welding procedure duringthe initial assembly can be factored into the dimensions of thecomponent parts. However, in view of the repeat welding procedurerequired each time a damaged bearer is cut out and replaced by a newbearer, an uncontrollable amount of damage to the grain texture of thetubular recess of the connector results. This gives rise to a largedecrease in the original strength of the material in the heat affectedzone and a danger of fracture of the bearer joint during heavy loadconditions.

This is particularly problematic in the situation where the bearermember is part of a segmented longitudinal bearer assembly, since inthis situation, it is taken for granted that the less stiff and moreeasily deformable forward bearer members of the longitudinal bearerassembly will necessarily be replaced during repairs after an accident.Further, the forward bearer members may even need to be replaced one ormore times for normal wear or fatigue during the lifetime of thevehicle. The welding procedures repeatedly required in this case wouldunacceptably weaken the joint by progressive structural change in thezone of thermal influence of the material of the aluminum alloy.

While it is conceivable to incorporate an acceptable safety factor intothe initial design of the bearer joint such that the wall thicknesses ofthe component parts are sufficiently large to compensate for theaforesaid severe decrease in strength caused by successive weldingprocedures, this is not a practical solution in view of the additionalcost and weight involved. Furthermore, it is desirable to provide thecustomer with a vehicle body which retains its original strength evenafter repairs.

German patent document DE 3 740 402 discloses another design for a frontlongitudinal bearer assembly which comprises two longitudinal bearermembers disposed forwardly of the front suspension mounting.

Here too, the forwardmost longitudinal bearer member is designed as adeformation element such that in the event of a minor collision, it willdeform more easily than the adjacent rearwardly disposed longitudinalbearer member. The longitudinal bearer members are arranged insuccession and are connected together at abutting ends or bearingsurfaces. The abutting bearing surfaces are designed as rotationalsurfaces in the transverse direction. A central, axially aligned boltconnection is used to join the abutting bearing surfaces of the twolongitudinal-member portions.

This configuration is especially advantageous when the longitudinalbearer members are formed as extruded aluminum sections, since theeasily accessible bolt connection permits quick and simple replacementof a deformed forward longitudinal bearer member after a minorcollision. Also, the strength loss problems associated with thereplacement of aluminum welds is not present here. However, the cost ofthe bolt connections used in this design are relatively high.

THE INVENTION OBJECTS

It is therefore a primary object of the invention to provide an improvedaluminum longitudinal bearer assembly in a vehicle frame of the typehaving a graduated stiffness characteristic which increases towards themiddle of the vehicle wherein a bearer joint is formed by the fittedinsertion and welded connection of a first, forwardly disposed andeasily deformable hollow section bearer member within a cast aluminumreceiving socket of a connector, and wherein the first bearer member canbe easily and inexpensively replaced without compromising the originalstrength of the bearer joint.

It is another object of the invention to provide a repair kit whichincludes a replacement front bearer member and a specially adaptedfitted insert for replacement of a damaged front bearer member andwhich, in combination, provide a sturdy, reinforced connection to thereceiving socket of the bearer joint.

It is another object of the present invention to provide a method forreplacement of a deformed front bearer member in a aluminum longitudinalbearer assembly of the type herein described which is low cost and easyto implement in existing vehicle body designs assembled from extrudedaluminum frame components.

Other and further objects will become evident from the following writtendescription, drawings and claims appended hereto.

DRAWINGS

FIG. 1 is a partial schematic view in side elevation of the front regionof a vehicle showing the front bearer structure of a vehicle body with atwo-part front longitudinal bearer assembly.

FIG. 2 is an enlarged isometric view of the improved longitudinal bearerjoint of the present invention showing a first cylindrical longitudinalbearer member fitted within a receiving socket.

FIGS. 3-5 show the requisite repair kit components for the reinforcedreplacement of a deformed bearer member of a longitudinal bearer jointwherein:

FIG. 3 is an isometric view of a replacement front longitudinal bearermember;

FIG. 4 is an isometric view of an insert having means for receiving ascrew or bolt fasteners; and

FIG. 5 is an isometric view of the receiving socket shown after theoriginal transverse weld seam which connects the front longitudinalbearer member to the socket has been cut out and the original bearermember (not shown) removed.

FIG. 6 is a partial cross section view in the axial direction of alongitudinal bearer joint after a repair has been completed showing theinsert fitted within the hollow interior of the replacement bearerwhich, in turn, has been fitted within the socket and bolted in place.

FIG. 7 is an exploded isometric view of the socket, insert andreplacement bearer member.

SUMMARY

The invention comprises a method and apparatus for the replacement of adamaged aluminum bearer member in a longitudinal bearer joint of a motorvehicle bodywork comprised of aluminum frame members and cast aluminumconnecting elements. According to a preferred embodiment of theinvention, the front bearer joint comprises a cast aluminum connectorfor joining a first, forwardly disposed extruded aluminum bearer memberto a second, rearwardly disposed aluminum bearer member. The connectorincludes a first tubular recess or socket for receiving the rearward endof the first, front bearer member. After insertion within the socket,the bearer member is fixed thereto by a surrounding transverse weld seamprovided to the forward edge of the socket.

Such a longitudinal bearer joint is produced during initial assembly. Toreplace a front bearer member which has become deformed as a result of aminor collision, it is not safe to repair the joint by simply separatingthe weld seam, inserting a new bearer member and reweld the componentparts, since a repair in this manner would result in an undesirabledecrease in the original strength of the aluminum material in theheataffected zones.

According to the invention, a longitudinal bearer member joint istherefore proposed wherein the socket end of the cast aluminum connectoris provided with a plurality of reinforced holes spaced apart along itsperimeter edge. Also provided is a repair kit which includes areplacement bearer member and an insert piece in the form of a nutplate. In use, the insert is fitted within the hollow interior of thereplacement bearer member, which is then fitted within the socket. Theinsert and replacement bearer are also provided with holes which arespaced for alignment with the threaded holes of the socket. The threecomponents are then secured together by screw or bolt fasteners. Theholes of the insert are preferably threaded.

The initial assembly of such a member joint can be carried out rapidlyand economically by the manufacturer by means of a weld. In repairworkshops, however, the special equipment required for a suitablereplacement weld is not always available. Also, repair personnel do notalways have the special expertise and/or training required for ensuringa strong weld of the aluminum components. This is particularly a concernwhen the welded joints are located at the critical points of an aluminumlongitudinal-member joint which are subject to very high loadconditions.

In addition, substantial preparation work and precautions must be takeninto consideration for fusion welding operations in the area of theengine compartment. For example, as it is necessary to provide enoughroom for the welding torch, removal of auxiliary units and/or the engineitself may be required. Also, great care must be taken during thewelding procedure in order to prevent against accidental fire andexplosion which may be caused by the welding torch. This prep work isentirely eliminated in the case where the fitted insert and screwedjoint repair method of the present invention is used, thus giving riseto significant time and cost savings.

Also, unlike the typical repair by welding, the fitted insert andscrewed joint repair method of the present invention can be easilyperformed by any workshop upon delivery of an appropriate repair kit.Further still, the problem of an impermissible reduction in materialstrength due to repeated welding operations does not occur, sincewelding is performed only once on the socket (i.e., during initialassembly by the manufacturer) and this measure may be taken into accountwhen dimensioning the component parts.

According to the invention, it is preferable to design the replacementbearer member as an elongated cylindrical member and the socket as acircular ring. However, other cross-sectional configurations of thesections are possible and these cross-sectional configurations areeasily produced in a simple manner by extrusion, for example.

As the repair and replacement of the bearer member is expedientlyenvisaged from the outset, the holes of the socket are preferablyreinforced by providing a thickening of the material in these regions.Also the thickened regions are preferably formed with flat bearingsurfaces for supporting the head portions of the bolt fasteners. Whilethe holes of the socket and replacement bearer are expediently presentfrom the outset, it would also be possible to drill these holes during asubsequent repair at the workshop.

In a preferred embodiment of the invention, the insert is designed as anextruded light metal circular plate-like member having a centralopening. The circumference of the insert is sized sufficiently large indiameter to ensure a positive and full surface contact with the innercylindrical surface of the replacement bearer member. The insert furtherincludes a longitudinal gap which extends from its outer peripheral edgeto its central opening in order to compensate for tolerancediscrepancies of the replacement bearer members. The plate-like inserthas a thickness dimension sufficiently wide for containing a pluralityof radially inward oriented threaded holes for receiving screw or boltfasteners. Also, to provide sufficient strength, each hole of the insertis reinforced by thickened material regions which extend inwardly adistance towards the central opening of the insert.

In accordance with the method aspects of the invention, a damagedlongitudinal bearer assembly is repaired as follows. First, the bearerjoint is disassembled by cutting the weld seam which joins the first,forward longitudinal bearer member (which has been deformed as a resultof a minor accident) to the socket. Next, the replacement frontlongitudinal bearer member is fitted with the plate-like insert at oneend, with the threaded holes of the insert coaligned with the holes ofthe replacement bearer member. The replacement bearer member and insertcombination is then fitted within the socket and is secured thereto byscrew fasteners or threaded bolt connectors directed through thecoaligned holes of the socket, bearer member and insert.

DETAILED DESCRIPTION OF THE BEST MODE

The following detailed description illustrates the invention by way ofexample, not by way of limitation of the principles of the invention.This description will clearly enable one skilled in the art to make anduse the invention, and describes several embodiments, adaptations,variations, alternatives and uses of the invention, including what wepresently believe is the best mode of carrying out the invention.

FIG. 1 is a schematic cross section view of a vehicle 1 which shows, inside elevation, the front region of the bearer structure of the vehiclebody, designated generally at reference numeral 2. The bearer structure2 includes a front longitudinal bearer assembly 3 which consists of aplurality of abutting end-to-end connected light metal structuralmembers which include: a first or forwardmost front longitudinal bearermember 4; an adjacent second longitudinal bearer member 5; a sidedeviation 6 which extends from the rear end of bearer member 5 to thebase of the front door pillar or front door post 8; and a bottom sill 9which connects to the rearwardly disposed end of the side deviation 6.

The first longitudinal bearer member 4 and the second longitudinalbearer member 5 are joined together by a cast light metal connector 15.The connector 15 includes a bottom recess portion or socket 16 adaptedfor the fitted insertion of the rearward end of the first longitudinalbearer member 4. The connector 15 also is preferably formed with anattachment fitting along its upper surface for connection to the frontsuspension strut 10. The connector 15 preferably comprises a multipiececonfiguration, such as, for example two half shell portions which jointhe adjoining bearer ends in clam shell fashion. The entire strut 10 maybe formed integral with one half shell portion of the connector 15.

The front suspension strut 10 supports a shock absorber 11 and is bracedby another, substantially upright bearer member 12 which extendsupwardly from the right or rear portion of the second longitudinalbearer member 5. The bearer member 13 connects the upright bearer 12 tothe middle region 14 of the door post 8 to complete the front region ofthe bearer assembly 2.

FIG. 2 is an enlarged isometric view of the connector 15 and socket 16shown with the first bearer member 4 inserted within the socket 16. Inthe preferred embodiment, the bearer member 4 is cylindrical in crosssection and is sized for snug fit engagement within the correspondingsocket 16 of the connector 15. Upon initial assembly at the factory, thefirst bearer member 4 is secured to the connector 15 by welding asurrounding weld seam 17 at the front edge of the socket 16. While thisarrangement represents the preferred method of initial assembly of thebearer joint, it is understood that a firm connection may also be madeby other conventional means, such as for example, screw or boltfasteners. Even at this stage, however, a plurality of thickenedmaterial portions having flat contact surfaces 18 and holes 19 areprovided in offsetting arrangement along the outer periphery of thesocket 16.

With reference now to FIGS. 3-7 the method aspects of the invention willnow be described. After an accident below a predetermined level ofseverity whereby only the first, front longitudinal bearer memberundergoes deformation, the deformed bearer member is separated from thesocket 16 by cutting the weld seam 17 after which it is removed. Thisresults in the exposed socket 16 shown in FIGS. 5 and 7.

FIGS. 3-4 and 7 show a repair set which is used in carrying out theinvention. The repair set comprises a replacement front longitudinalbearer member 4 which is provided with a plurality of holes 20 (only onehole is clearly visible) located along the periphery of one end of thebearer member 4 (see FIG. 3). The number and placement of holes 20 onthe bearer member 4 correspond to the number and placement of holes 19on the socket 16. While in the preferred embodiment shown, four holesare present in each component (socket 16 and bearer member 4), it isunderstood that as little as two holes may be provided or alternatively,a greater number of holes may be used depending on the space available.

The repair set also contains an insert 21 (FIGS. 4 and 7). The insert 21is designed as a plate-like member having an outer cylindrical contactsurface 22 and a central opening 23. To allow for tolerance variationsof the inner cylindrical dimension of different replacement front bearermembers, the insert is provided with a gap 24 which extends from theouter periphery or contact surface 22 to the central opening 23. Aplurality of radially oriented threaded holes 26 are arranged offsetalong the circumference of the contact surface 22 in thickened materialregions 25 of the insert 21.

In use, the insert 21 is fitted within the longitudinal bearer member 4(FIGS. 3 and 7) such that the threaded holes 26 of the insert 21 arealigned with the holes 20 of the replacement bearer member 4. Thisarrangement is then inserted within the socket 16 and the coalignedholes 20, 26 are then brought into alignment with holes 19 of the socket16.

Finally, the arrangement, consisting of the longitudinal bearer member4, the insert 21 and the socket 16, is screwed together with the aid ofa plurality of screw fasteners or threaded bolts 27, thereby providing afirm and positive bearer joint between the socket 16 and the bearermember 4.

The invention therefore provides a simple and economical design for animproved bearer joint and a method of repair wherein the originalstrength of the joint is not compromised during a replacement of abearer member which was originally secured by a welded joint. Theinvention has particular utility in an aluminum bearer assembly whererepair by thermal welding is problematic.

It should be understood that various modifications within the scope ofthis invention can be made by one of ordinary skill in the art withoutdeparting from the spirit thereof. For example, while the preferredembodiment of the invention has been described in detail with particularreference to the repair of a damaged front longitudinal bearer assembly,it is understood that the teaching principles of the invention may alsobe applied to other aluminum bearer assemblies of a vehicle bodyworkwhich are subject to buckling along a common longitudinal axis. Wetherefore wish our invention to be defined by the scope of the appendedclaims as broadly as the prior art will permit, and in view of thespecification if need be.

    ______________________________________                                        PARTS LIST                                                                    ______________________________________                                        1.    Motor Vehicle    23.   Central Opening                                  2.    Vehicle Body     24.   Gap                                              3.    Longitudinal Bearer                                                                            25.   Thickened Regions                                      Assembly         26.   Threaded Holes                                   4.    Front Longitudinal                                                                             27.   Bolt                                                   Bearer Member                                                           5.    Rear Longitudinal                                                             Bearer Member                                                           6.    Side Deviation                                                          7.    Foot                                                                    8.    A-Pillar                                                                9.    Bottom Seal                                                             10.   Front Suspension Strut                                                  11.   Shock Absorber                                                          12.   Upright Bearer Member                                                   13.   Bearer Member                                                           14.   Middle Region                                                           15.   Connector                                                               16.   Cylindrical Socket                                                      17.   Weld Seam                                                               18.   Thickened Region                                                        19.   Hole                                                                    20.   Hole                                                                    21.   Insert                                                                  22.   Cylindrical Contact                                                           Surface                                                                 ______________________________________                                    

We claim:
 1. Method for replacing a bearer member in a motor vehiclebody longitudinal bearer joint which includes a cast light metalconnector having a tubular socket sized for receivingly engaging one endof a first, forwardly disposed extruded light metal longitudinal bearermember originally secured in place by a surrounding transverse weld seamjoining said first bearer member to a front edge of said socket, saidmethod comprising in operative sequence the steps of:a) separating theweld seam; b) removing the first bearer member; c) providing said socketwith a plurality of holes spaced apart along its circumference adjacentsaid front edge; d) inserting into the socket a replacement bearermember kit assembly which includes:i) a replacement hollow-sectionbearer member having a first end provided with a plurality of holesspaced for coalignment with said holes of said socket; ii) an insertpiece fitted within a hollow interior of said replacement bearer memberfirst end and having a plurality of threaded holes spaced apart forcoalignment with said holes of both said replacement bearer member firstend and said socket; e) aligning the respective holes of said socket andsaid replacement bearer member with the threaded holes of said insertpiece; and f) securing said replacement bearer member and insert pieceto said socket with threaded bolt fasteners.
 2. The method according toclaim 1 wherein the first bearer member and the socket are manufacturedfrom aluminum.
 3. The method according to claim 2 wherein:a) the firstbearer member and the replacement bearer member are configured aselongated cylindrical members; and b) the socket is circular in crosssection and includes an inner diameter sized to conform to an outerdiameter of the first bearer member and the replacement bearer member.4. The method according to claim 3 wherein:a) the socket includesthickened portions of material adjacent each hole thereof forreinforcement; and b) each of the thickened portions of materialincludes a flat bearing surface for supporting a bolt head correspondingto one of the threaded bolt fasteners.
 5. The method according to claim4 wherein the insert piece is a nut plate and includes:a) an outerperimeter surface configured for full contact with an inner surface ofthe replacement bearer member; b) a central opening; and c) a gapextending between said outer perimeter surface and said central openingto facilitate the fitted insertion of said nut plate within the hollowinterior of replacement bearer members of varying inner tolerances. 6.The method according to claim 1 wherein:a) the first bearer member andthe replacement bearer member are configured as elongated cylindricalmembers; and b) the socket is circular in cross section and includes aninner diameter sized to conform to an outer diameter of the first bearermember and the replacement bearer member.
 7. The method according toclaim 6 wherein:a) the socket includes thickened portions of materialadjacent each hole thereof for reinforcement; and b) each of thethickened portions of material includes a flat bearing surface forsupporting a bolt head corresponding to one of the threaded boltfasteners.
 8. The method according to claim 7 wherein the insert pieceis a nut plate and includes:a) an outer perimeter surface configured forfull contact with an inner surface of the replacement bearer member; b)a central opening; and c) a gap extending between said outer perimetersurface and said central opening to facilitate the fitted insertion ofsaid nut plate within the hollow interior of replacement bearer membersof varying inner tolerances.
 9. The method according to claim 4wherein:a) the socket includes thickened portions of material adjacenteach hole thereof for reinforcement; and b) each of the thickenedportions of material includes a flat bearing surface for supporting abolt head corresponding to one of the threaded bolt fasteners.
 10. Themethod according to claim 9 wherein the insert piece is a nut plate andincludes:a) an outer perimeter surface configured for full contact withan inner surface of the replacement bearer member; b) a central opening;and c) a gap extending between said outer perimeter surface and saidcentral opening to facilitate the fitted insertion of said nut platewithin the hollow interior of replacement bearer members of varyinginner tolerances.
 11. The method according to claim 1 wherein the insertpiece is a nut plate and includes:a) an outer perimeter surfaceconfigured for full contact with an inner surface of the replacementbearer member; b) a central opening; and c) a gap extending between saidouter perimeter surface and said central opening to facilitate thefitted insertion of said nut plate within the hollow interior ofreplacement bearer members of varying inner tolerances.